"The purpose is to draw you out. The purpose is if there's police officers, air marshals, DEA, FBI, they want to draw you out," former U.S. Air Marshal Steve Theodoropoulos said.

The memo outlines an incident that happened in September on a flight from Washington, D.C. to Orlando International Airport.

During the flight, a group of men created a ruckus. One of the men ran from his seat in coach towards the flight deck door and the front bathroom. He stayed in the bathroom for a “considerable length of time,” according to the memo.

Other men got up and proceeded to move about the cabin, according to the memo. Some of the men changed seats and others opened overhead bins.

“They appeared to be trying to occupy and distract the flight attendants,” the memo said.

According to a U.S. Airlines news release, the men were detained because of the “suspicious activity.”

Theodoropoulos said he used to fly the same flight.

"It's a high-level plane. A lot of VIPS, senators, congressmen. So if you're going to target a plane, you're going to target the one you think air marshals are on," Theodoropoulos said.

Transportation agents said an investigation was conducted into the incident involving local police, TSA and federal law enforcement agencies. The individuals involved were also checked on all government databases, the aircraft was inspected and no irregularities were found.

The memo warns pilots and flight attendants to be extra vigilant and to never be pressured into taking a flight that makes them uncomfortable.

"The American public is at risk and we're getting ready to move into the busiest time of year. We all need to be on alert," Theodoropoulos said.